The proposed research deals with the perceptual recognition of briefly-presented pictures of real-world scenes. Theoretical interest centers on the development of a visual grammar which would describe the perceptual employment of six kinds of relations between an object and its setting: support, interposition, relative size, probability of occurrence in the scene, and position in the scene. In addition, the centrality of the object to the theme of the scene will be studied. The research is also designed to aid in the development of a model which would assign the locus of effects of these relations to stages in an information-processing sequence. The primary experimental strategy is to violate the above relations, so that objects appear to be floating, transparent, too large or too small, unlikely to be in the scene, or unlikely to occupy a given position in the scene. The effects of these violations on the speed (reaction time) and accuracy of 1) detecting an object undergoing a violation, and 2) detecting the presence of the violation itself, will be measured as a function of a number of variables including the number of violations, camouflage, target and positional uncertainty, and scene presentation duration. Experiments will also be performed to assess the effects of laterality, memory, depth gradients and photographic vs. drawn representations. BIBLIOGRAPHIC REFERENCES: Spector, A., and Biederman, I. Mental set and mental shift revisited. American Journal of Psychology, 1976, 89, 669-679. Biederman, I. On processing information from a glance at a scene: some implications for a syntax and semantics of visual processing. Proceedings of the ACM/SIGGRAPH NSF Workshop on User-Oriented Design of Interactive Graphics System, 1977, In press.